1. Field of the Invention
The invention relates in general to a scanning apparatus, and more particularly to a scanning apparatus capable of reducing the abrasion of the loading glass and thus improving the quality of the scanning image.
2. Description of the Related Art
With the progress and evolution of technology, the integration and application of multi-media have become the current trend. Multimedia is the use of computers to present different types of information, such as text, images and sound, in an integrated way. Several multi-media devices capable of capturing images and sounds are therefore developed. In terms of the image processing, the scanning apparatus is a common tool for users to capture images.
Referring to FIG. 1A, a lateral view of a conventional flatbed scanner is shown. The flatbed scanner includes a housing 102, and a cover 104. The housing 102 includes a scan flatbed 106 or a so-called window area. A loading glass 108 is installed at the scan flatbed 106 for loading a to-be-scanned document 111. The scanning operation is performed as the following. The to-be-scanned document 111 is placed on the scan flatbed 106 and then the cover 104 is closed. A photoelectric sensing device 110 in the housing 102 is driven to sense the to-be-scanned document 111. A light-sensing module 112 in the photoelectric sensing device 110 then transforms the received image signals to electric signals. The electric signals are further transmitted to a motherboard 116 by a flat cable 114 so that the images sensed by the light-sensing module 112 can be output. The light-sensing module 112 can be a charge coupled device (CCD) or a contact image sensor (CIS) to achieve the above-mentioned purpose.
After the first signals in the light-sensing module 112 are output, the photoelectric sensing device 110 is further shifted slightly to scan the left part of the to-be-scanned document 111 by a step motor (not shown). Subsequently, the light-sensing module 112 is driven again to sense the to-be-scanned document 111. The sensed image signals are then transmitted by the flat cable 114 and output by the motherboard 116. By performing the procedure mentioned above repeatedly, the scanning progress can be completed step by step. The procedures described above can be applied to both reflective documents and transmissive documents since these two kinds of documents are different in the locations of the light sources (not shown) but the same in the progress of photoelectric sensing devices 110 to sense the documents and the connection between the photoelectric sensing device 110 and the flat cable 114. Therefore, the theorems for capturing images of two kinds of documents are also the same.
Referring to FIGS. 1A and 1B, a structural diagram of the connection between the photoelectric sensing device and the motherboard in a conventional flatbed scanner is shown. The flat cable 114, which is usually a soft cable, is located under the loading glass 108. The flat cable 114 is bent around the bottom of photoelectric sensing device 110; one terminal A of the flat cable 114 is connected to the photoelectric sensing device 110, and the other terminal B is connected to the motherboard 116. Therefore, in the natural condition, the flat cable 114 will form a raised part 118 with a height h. Because scanners nowadays are designed to be thinner and thinner, when scanners are fabricated, the raised part 118 of the flat cable 114 will easily touch the loading glass 108 at the scan flatbed 106 as shown in FIG. 1C. Subsequently, when the step motor drives photoelectric sensing device 110 to pre-scan or scan the to-be-scanned document 111, the raised part 118 of the flat cable 114 will rub against the loading glass 108 and result in friction traces at the loading glass 108 as time goes by. The friction traces on the loading glass 108 will obscure the light to penetrate and result in shadow traces on the scanning images. Therefore, the quality of scanning images is reduced largely.